At a typical refuelling station or other refuelling system, fuel is pumped from a storage tank to a recipient, such as a vehicle fuel tank, via a fuel dispenser. A nozzle in the form of a dispensing gun is positioned at the end of the fuel dispenser and may carry out multiple functions, including for example safe and efficient dispensing of fluid, providing automatic shut-off such that the flow of fuel is terminated when the vehicle tank is sufficiently full, preventing improper operation of the dispenser, and enabling the nozzle to be temporarily held in the open/dispensing position.
Conventional dispensing guns for dispensing fuels, such as petrol or diesel, may often suffer from spillage of fuel due to fuel dripping from the delivery tube after the delivery of fuel has been stopped, for example by an automatic shut-off arrangement. Even though this is not desirable and may present a small risk of flammable liquid being subjected to an unprotected environment it is generally acceptable with a small leakage of such fuels.
However, in light of the development of new alternative fuels, even such a small leakage may have a detrimental effect and must be avoided. Therefore, various solutions of dispensing guns comprising for example complex outlet valve arrangements and/or means for securing a liquid tight coupling between the dispensing gun and the recipient of the fuel have been developed in recent times. The outlet valve arrangement and/or said securing means of the dispensing guns ensures that no leakage can occur, for example by ensuring that no liquid can be present outside of the outlet valve of the dispensing gun after a dispensing procedure. This can for example be achieved by ensuring that a dispensing procedure is only possible when a coupling part of the dispensing gun has been firmly coupled to a corresponding coupling part associated with the fuel tank of a vehicle, and that the dispensing gun cannot be released before the outlet valve has been completely closed. The outlet valves are often some type of poppet valve.
It is previously known to provide a liquid tight coupling of a dispensing gun to a male coupling of a recipient by the use of locking balls of a female coupling of the dispensing gun falling into a groove or recess of the male coupling body. However, in such previously known dispensing guns, the locking of the dispensing gun to the male coupling also influence the outlet valve of the dispensing gun such that a flow of liquid to be dispensed is automatically achieved or at least enabled as soon as the coupling is effectuated. However, in some applications, for example public refuelling stations and especially in case the fuel is a highly flammable liquid, there is a need to be able to start, stop and regulate the flow of liquid only after a liquid tight connection is made.
GB 2068069 A discloses an example of such prior art, but in the form of a pipe coupling. The female coupling member includes a valve body and a displaceable sleeve which in a sealing position is designed to seal against the valve body, via a sealing element on the latter. On insertion of a male coupling member into the female coupling member, the sleeve is pushed back by engagement between a surface in the male member and a shoulder on the sleeve. The female coupling member and the male coupling member are locked to each other by means of locking balls. The pipe coupling disclosed in GB 2068069 A however has the drawback that when the female coupling and the male coupling are locked to each other, the flow path is completely open.